Studying effect of location and resistance of inter-turn faults on fault current in power transformers

Inter-turn (turn-to-turn) fault is one of the most important failures which could occur in power transformers. This phenomenon could seriously reduce the useful life length of transformers. Meanwhile, transformer protection schemes such as differential relays are not able to detect this kind of fault. This type of fault should be studied carefully to determine its features and characteristics. In this paper the effect of fault location and fault resistance on the amplitude of fault current is studied. It is found that change of fault location along the winding has considerable effect on fault current amplitude. It would also be shown that, even small fault resistance could have major effect on fault current amplitude. In this paper, a real 240/11 kV, 27 MVA transformer is used for simulation studies.